Isthmus Reef
Isthmus Reef, located on Catalina Island in the United States, is a sought-after dive site for beginners and open water students. This popular spot is only accessible by boat, adding to its allure. Its sheltered location and shallow depth make it an ideal choice for those who are new to diving.
Divers exploring Isthmus Reef will be greeted with a diverse marine life, including a variety of kelp fish species such as garibaldi, sheepshead, senorita wrasse, and kelpfish. Additionally, there is an abundance of sea urchins, sea stars, and gobies, creating a vibrant and captivating underwater environment.
With a visibility of approximately 12 meters and a maximum depth of 16 meters, divers can enjoy clear waters to fully appreciate the beauty of Isthmus Reef. This close proximity to Two Harbors in Los Angeles County, California further adds to the convenience and accessibility of this remarkable dive site.
Divers exploring Isthmus Reef will be greeted with a diverse marine life, including a variety of kelp fish species such as garibaldi, sheepshead, senorita wrasse, and kelpfish. Additionally, there is an abundance of sea urchins, sea stars, and gobies, creating a vibrant and captivating underwater environment.
With a visibility of approximately 12 meters and a maximum depth of 16 meters, divers can enjoy clear waters to fully appreciate the beauty of Isthmus Reef. This close proximity to Two Harbors in Los Angeles County, California further adds to the convenience and accessibility of this remarkable dive site.
Diving Conditions Score for Isthmus Reef
5.8
AverageAverage conditions, be alert.
The score is based on a calculation of the current weather and sea conditions.
Dive Site Overview for Isthmus Reef
Depth
16m
Visibility
12m
Experience Level
beginner
Weather Conditions for Isthmus Reef
Wave Height
0.84m
Wind Speed
14.8 m/s
Water Temp
20.2°C
Visibility
17.9km
Cloud Cover
49%
Wave Period
11.55s
Air Temperature
19.2°C
Precipitation
0 mm
Detailed 7-Day Diving Forecast for Isthmus Reef
Alpha
Dive Score Chart for Isthmus Reef
Best time to dive: 15:00 with score 8.077507507507507/10. Water conditions: Waves 0.82m, Wind 4.4 m/s.Best night dive time: 19:00 with score 7.27463768115942/10.
Chart showing hourly dive conditions including wave height, wind speed, water temperature, and visibility throughout the day.
Sunrise at Isthmus Reef: 06:00
Sunset at Isthmus Reef: 18:00
Optimal diving conditions at Isthmus Reef are affected by daylight hours. Sunrise occurs at 06:00 and sunset at 18:00, which impacts visibility and water temperature for scuba diving and snorkeling.
Best Overall
15:00Score: 8.1/10
Waves: 0.82m (11.1s), Wind: 4.4 m/s
Best Night
19:00Score: 7.3/10
Waves: 0.82m, Wind: 6.2 m/s
Seasonal Analysis for Isthmus ReefAlpha
Historical patterns and best seasons for diving at Isthmus Reef
The dive score combines all factors to rate overall diving conditions throughout the year. Higher scores indicate better diving conditions.
Monthly Dive Score Analysis - Seasonal Diving Conditions
Higher values indicate better diving conditions
Seasonal DiveScore Chart
This chart displays monthly diveScore data throughout the year, showing seasonal patterns. The data is presented as a bar chart with an overlaid line graph.Dive scores range from 1 to 10, with 10 being optimal conditions.
Higher values indicate better diving conditions
Best Season for Isthmus Reef
Winter
Avg. Score: 10.0/10
Winter offers the best overall diving conditions with calmer seas and better visibility, despite cooler temperatures.
Best Months for Isthmus Reef
January
Score: 10.0
February
Score: 10.0
March
Score: 10.0
Ideal Conditions for Isthmus Reef
Water Temp
23.3°C / 73.9°F
June
Visibility
20.1m / 65.9ft
October
Wave Height
0.2m / 0.7ft
January
Wave Period
8.0s
January
Seasonal Insights for Isthmus Reef
Isthmus Reef shows typical northern hemisphere patterns with June being the warmest month (23.3°C) and December the coldest (19.3°C). The calmest conditions typically occur in January with average wave heights of 0.2m and wave periods of 8.0s. The most comfortable wave conditions are in January with a low wave steepness ratio, creating gentler swells. January offers the longest wave periods (8.0s), creating more comfortable and predictable conditions for boat entries and exits. Ocean currents are slowest in January (0.5m/s) and strongest in January (0.5m/s). January is usually the driest month with 0.0mm of precipitation. For beginners, the best time to visit would be during January to March, when ocean conditions are calmer with long-period waves and currents are typically weaker. Experienced divers might enjoy the challenges and potentially better visibility during the shoulder seasons, with moderate currents that can improve marine life encounters.
Last updated: 1 min. ago - Jun 22, 2026
Note: This dive site is not a verified dive site. Please dive with caution. This dive site might have incorrect information by the community.
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